Method of catalytic oxidation of turpentine oils



PatentedFeb.1i,leIi6 7 2,030,802

UNITED. STATES PATENT OFFICE I I v "F OX IDATION OI' I I WaltherSchranth, Berlin-Dahlem, Germany,

assignor to Dentsche Hydrierwerke Aktiengelellschaft,Be'rlin-Charlottenbnrg, Germany,

a corporation of Germany No Drawing. Application my 1a, 1934, Serial no.7 720,301. in Germany May 29, 19::

9. Claim. (0]. 260-116) The present invention relates 'to theproducsurface can be obtained by applying the catalysts tion of maleicacid and has for an object to pro-- to suitable carriers, as forexample. aluminum yide an effective method of producing maleic acidgravel, porcelain, asbestos, pumice stone. diatoirom turpentine oils.Another object is to promaceous earth, clay and the like. The catalystsvide an effective maleic acid product. may also be combined with xeoliteand similar The invention. provides a method whereby any. substances.kind of turpentine oil, such, for example, as 5111- In order to avoidtoo violent a reaction the fate turpentine oil, pine ,oil, or extractionturpenoxygen supplied for reaction can be diluted with tine oil can beused as raw'material in the proinert gases such as nitrogemwater vaporand the 10 duction of maleic acid of satisfactory purity. The like.These gases are sufliciently inert to the lil sulfate turpentine oilwhich is an inexpensive material present in the reactionchamber.by-product of the sulfate process in the cellulose The reactionconditions can be considerably manufacture is especially appropriate andreadvaried. Certain advantages are obtained by causily available. ingthe reaction to occur at slightly-super-at- The turpentine oils underconsideration are mospheric pressures. The time of the reaction 15 ofcomplicated molecular structure, combining depends upon the conditionssuch as the kind. both the cylic and side chain arrangements. Beandeffectiveness of the catalysts, the temperacause of this complexmolecular structure, itwas ture in the reaction chamber and theconcentra hardly to be expected that by a relatively simple tion of thestarting material. procedure a conversion to maleic acid with agood Ifcatalysts which cause a reduction of the yield of maleic acid could beobtained and espetemperature during reaction such as tin salts cially bya relatively simple procedure. are employed, lower temperatures maysatisfac- .It has been discovered, however, in accordance. torily bemaintained in the reaction chamber. with the present invention thattheseturpentine Ordinarily, however, the temperature of the reoils canbe oxidized to' produce maleic acid by a action should be of the orderof 250 to 500C. reaction carried on in the vapor phase at tem- Probablytemperatures'of 340 to 440 C. represent peratures oi the order or 250 to500 C. the best convenient temperatures for commercial In accordancewith the preferred embodiment operation. The temperature may toadvantage of the invention these oils in vaporous condition bemaintained .between 350 to 400 C. as in the are reacted with oxygen inthe presence of oxidaexample hereinafter described. 30 tion catalystswhich favor the oxidation reac- When a large excess of' air, as forexample 10 tion. Air may eflectively be used as the source of to 50times that necessary to supply ongen for oxygen and the reaction isimproved if a considthe reaction, is used, the range of temperatureerable excess of air over that theoretically required can be extendedfrom the figures above indicated tor the reaction is present. Forexample the air while still obtaining eifective yields. It is, there- 5mixed with the vapors of the turpentine oil may fore, possible tooperate the process successfully be of theorder of 10 to 50 times thatnecessary to without the necessity for complicated equipment supply theoxygen taking partin the reaction. for automatically maintaining anexact desired Various catalysts may be used. Particularly temperature.

40 suitable are the oxides of poly-valent metals Example-Sulfateturpentine oil is sprayed 40 which form more. or less stab'le compoundsin (atomized) into the reaction chamber-at a temseveral stages ofoxidation and are of acid charperature above 200 C. where it is mixedwith hot acter as, i'or example, vanadic acid and its salts air andpassed in contact with a catalyst heated such as copper-, silver-,.tinand bismuth-vanato 350 to 400" C. The catalyst may consist of diate.Oxides of molybdenum, wolframlte, uravanadic acid on porcelain fragmentsand maybe 5 nium, manganese, tin and the like may also be activated withthorium oxide and'phosphoric acid.

used. Also, these metal oxides may be combined The volume of the air mayapproximate 100 cuwith vanadium oxides to provide a suitable cata-- bicmeters per kilogram of oil and its temperalyst'. As activating additionoxides of nickel ture as'sup'plied should be such as to keep'the.

thorium, iron, copper. bismuth,- cobalt, etc.-have temperature in thereaction chamber within the proved to be of considerable value, thee'flectivelimits indicated. 1 V

ness of the catalyst can be improvedby the ad-'- The maleic acid, or themaleic acid anhydride dition of inorganic oxygen acids such as borlcwhich also may be formed in. the reaction, is and-phosphoric acid. 7 Vwashed from the reaction 8 by means of wa- 55 Economy 0! the catalystsand a greater exposed ter. as for example in a water tower. H

The foregoing particular description is illustrative merely-and notintended as defining the limits of the invention.

I claim- 1. The method of producing maleic acid which comprises mixingturpentine oil vapor with air in excess of that required for there-action and contacting the mixture with an oxidizing catalyst selectedfrom the group consisting of the oxides of vanadium, molybdenum,tungsten, uranium, manganese,'and tin having acid character and themetal salts of the acids of said oxides to oxidize the turpentine oil'tomaleic acid.

ducted at super atmospheric pressure. I

3. The method of producing maleic acid which comprises mixing turpentineoil vapor with air in excess of that required for the re-action andcontacting the mixture with an oxidizing catalyst selected from thegroup consisting of the oxides of vanadium, molybdenum, tungsten,uranium, manganese, and tin having acid character and the metal salts ofthe acids of said oxides together with an activating agent selected fromthe group consisting of the oxides of nickel, thorium, iron, copper,bismuth and cobalt to oxidize the turpentine .oil to maleic acid. l

4. The method of producing maleic acid which comprises mixing turpentineoil vapor with air in excess of that required for the re-action andcontacting the mixture with an oxidizing catalyst selected from thegroup consisting of the oxides of vanadium, molybdenum, tungsten,uranium, manganese, andti'n having acid character and the metal salts ofthe acids of said oxides together with an inorganic acid selected fromthe group consisting of boric and phosphoric acids to oxidize theturpentine oil to maleic acid.

5. The method of producing maleic acid, as defined in claim 1, whereinthe temperature of the re-action is between about 350 and about 400 C.

6. The method of producing maleic acid, as

defined in claim 1, wherein the temperature or the re-action is betweenabout 340 and about 7. The method of producing maleic acid whichcomprises mixing turpentine oil vapor with air in excess of thatrequired for the reaction and contacting the mixture with an oxidizingcatalyst heated toapproximately 350 to 400 C., said catalyst consistingof vanadic acid on porcelain fragments activated with thorium oxide andphosphoric acid, the volume of the air approximating 100 cubic metresper kilogram of oil va- 8. The method of producing maleic acid whichcomprises reacting turpentine oil in the vapor phase mixed with oxygenof the order of ten to fifty times that necessary for the re-action at atemperature of 250 to 500 C. in the presence of an oxidizing catalystselected from the group consisting of the oxides of vanadium,molybdenum,

' tungsten, uranium, manganese and tin having acid character and themetal salts of the acids of such oxides.

9. The method of producing maleic acid which comprises reactingturpentine oil in the vapor phase with oxygen at a temperature of 250 to500 C. in the presence of a catalyst comprising 'a metal salt of vanadicacid.

WALTHER SCI-IRAUTH.

